Keystone Review #2 - Cell Transport & Homeostasis

The movement of oxygen molecules from an area of higher concentration to an area of lower concentration is known as __________.

• diffusion
• osmosis
• respiration
• photosynthesis

Which of the following should pass most easily through the plasma membrane?

• a protein

• a small lipid

• a sodium ion

• a water molecule

Why is the phospholipid bilayer only partially permeable to water?

• Water is repelled by the polar tails of the phospholipid.

• Water is repelled by the polar head of the phospholipid.

• Water is repelled by the hydrophobic tails of the phospholipid.

• Water is repelled by the hydrophobic head of the phospholipid.

Which is not a component of the plasma membrane?

• fatty acids

• phosphates

• amino acids

• nucleic acids

The calcium ion passes easily through the membrane of one cell but cannot cross the membrane of a second cell. Which part of the plasma membrane allows this substance to cross?

• Carbohydrate groups on the membrane allow ions to cross.

• The fatty acid tails of the phospholipids allow ions to cross.

• Protein channels in the plasma membrane allow ions to cross.

• Phosphate groups of the phospholipid bilayer allow ions to cross.

Which is not an example of passive transport?

• Carbon dioxide in a capillary crosses the alveoli membranes of the lungs.

• Oxygen dissolved in the blood crosses the phospholipid portion of the membrane of a red blood cell.

• Glucose molecules are transported by a carrier protein until its concentration on both sides of the membrane is equal.

• Sodium ions move through a protein channel until there is a higher concentration in extracellular fluid than the cytoplasm.

Which of the following is not involved in the transport of molecules by facilitated diffusion?

• ATP

• phospholipids

• protein channels

• concentration gradient

What is one way that facilitated diffusion differs from simple diffusion?

• Facilitated diffusion requires energy input.

• Facilitated diffusion requires membrane proteins.

• Facilitated diffusion requires a concentration gradient.

• Facilitated diffusion requires small, nonpolar molecules.

A pipe carries rainwater into a lake. The rainwater has picked up dissolved nitrates from surrounding lawns. Which of the following is a consequence of simple diffusion of nitrates in the lake?

• A concentration gradient of nitrates is created and maintained.

• The total amount of dissolved nitrate in the lake water decreases.

• Nitrate concentration decreases in some places and increases in others.

• Energy is required to move the nitrates from one end of the lake to the other.

The image shows a U-shaped tube with a semipermeable membrane separating the right and left sides. Each side is filled with equal volumes of water and different concentrations of solute. Which statement explains the change in water volume?

• Water moved to the right side, where solute concentration was originally lower.

• Water moved to the right side, where solute concentration was originally higher.

• Water and solute moved to the right side, where solute concentration was originally lower.

• Water and solute moved to the right side, where solute concentration was originally higher.